difficult to install updates or to delete unwanted softwarepackage libapt-pkg4.12 0.8.16~exp12ubuntu10.11 failed to install/upgrade: ErrorMessage: package libapt-pkg4.12 is already installed and configured

[Jan]

regular updates aren't possible and it is diffcult to deinstall unwanted software

ProblemType: Package
DistroRelease: Ubuntu 12.04
Package: libapt-pkg4.12 0.8.16~exp12ubuntu10.11
ProcVersionSignature: Ubuntu 3.2.0-49.75-generic 3.2.46
Uname: Linux 3.2.0-49-generic i686
ApportVersion: 2.0.1-0ubuntu17.3
Architecture: i386
Date: Tue Aug 6 19:00:26 2013
ErrorMessage: ErrorMessage: package libapt-pkg4.12 is already installed and configured
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
MarkForUpload: True
SourcePackage: dpkg
Title: package libapt-pkg4.12 0.8.16~exp12ubuntu10.11 failed to install/upgrade: ErrorMessage: package libapt-pkg4.12 is already installed and configured
UpgradeStatus: Upgraded to precise on 2013-02-15 (172 days ago)